| Project/Area Number |
07558286
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Osaka University |
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Principal Investigator |
YAMANAKA Tatsuhiko Institute of Laser Engineering, Osaka University, Professor, レーザー核融合研究センター, 教授 (80107143)
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| Co-Investigator(Kenkyū-buntansha) |
JITSUNO Takahisa Institute of Laser Engineering, Osaka University, Associate Professor, レーザー核融合研究センター, 助教授 (30162811)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Chemical surface reaction / Optical thin film / Aluminium oxide / Titanium dioxide / Anti-reflective coating / High-controllable thickness / Laser-induced damage / レーザー耐力 / TiO_2薄膜 / 多層膜コーティング / トリメチルアルミニウム[Al(CH_3)_3] / 自己停止機能 |
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| Research Abstract |
It is very expensive to make meter size multilayr optical films with high uniformity and high laser damage threshold by an evaporation method. In order to develop a cost-effective method, we have studied a chemical surface reaction technique applied an atomic layr epitaxy method. In the chemical surface reaction, the films can be easily deposited by introducing a reactant and an oxidizer alternatively, and the thickness can be precisely controlled only by the number of reactive cycles with a reaction chamber of which size is as large as substrate size. Aluminium oxide (Al_2O_3) films were grown using trimethylaluminium (TMA) as a reactant gas and hydrogen peroxide (H_2O_2) as an oxidizer for a low refractive index layr. Titanium dioxide (TiO_2) films were grown using tetrachlorotitanium (TiCl_4) and hydrogen oxide (H_2O) for a high refractive index layr.
The deposited film on glass plates showed very uniform distribution of thickness within 1% over 250-mm region which limited by a chamb
… More
er size. The results mean that this method is effective to grow the films with high uniformity and precise thickness for large optics. The refractive indices depended strongly upon the substrate temperature, and the growth rate depended upon the exhaust performance of the residual gas and upon the introduced pressure of oxidizers. The properties of films were not serious effected by other deposition parameters. These results suggest that this method can grow films by a stable and reproducible manor without any sensitive controls. Anti-reflective coatings consisting of Al_2O_3 and TiO_2 Layrs were deposited, and the optical characteristics were measured. The tested anti-reflective coatings are for 532-nm and 1064-nm light. Residual reflectivity of lower than 0.1% was easily obtained and was agreed well with the design value. The laser-induced damage threshold of Al_2O_3 and TiO_2 fulms was 7 J/cm^2 and 3.5 J/cm^2 at 1-ns, 1064-nm laser pulse, respectively. These films are applicable to lasers although some improvements are required for high power lasers such for laser fusion.
In conclusion, the developed chemical surface reaction method showed an excellent controllability in thickness and uniformity and was applicable for any large optical apparatus. It is expected to improve laser damage threshold for high power lasers. Less
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